How to copy position, size from one armature to another?
While we can easily copy a pose from one armature to another I don't think there is a way to copy edit bone changes from armature to armature. This would mean creating a python script is the way.

As editing bone data in bpy.data.armatures[x].bones doesn't seem to work, we can go into edit mode to collect the bone data from the source armature, then apply that data to each destination armature in edit mode.

So getting close to an exact answer would be the following script, you should only have to change the rig names at the top.

import bpy

source_rig = 'metarig'
dest_rigs = ['metarig.001','metarig.002']

############

bone_data = {}

def edit_rig(rigname):
    bpy.ops.object.mode_set(mode='OBJECT')
    bpy.ops.object.select_all(action='DESELECT')

    bpy.data.objects[rigname].select = True
    bpy.context.scene.objects.active = bpy.data.objects[rigname]
    bpy.ops.object.mode_set(mode='EDIT')

edit_rig(source_rig)
for b in bpy.data.objects[source_rig].data.edit_bones:
    bone_data[b.name] = (b.head.copy(), b.tail.copy(), b.roll)

for arm_name in dest_rigs:
    edit_rig(arm_name)
    for b in bpy.data.objects[arm_name].data.edit_bones:
        b.head, b.tail, b.roll = bone_data[b.name]

bpy.ops.object.mode_set(mode='OBJECT')